1. Field of The Invention
This invention relates to the art of earth boring and crude petroleum production. More particularly, the invention relates to well annulus packer tools and methods for improving the efficiency of downhole operations
2. Description of Related Art
Packers and bridge plugs are devices for sealing the annulus of a borehole between a pipe string that is suspended within the borehole and the borehole wall (or casing wall). Hereafter, the term “packer” will be used as a generic reference to packers, bridge plugs or other such flow channel obstructions. The functional purpose of a packer is to obstruct the transfer of fluid and fluid pressure along the length of a well annulus.
Certain well completion procedures call for a conduit link to the surface independent of a primary workstring flowbore provided by drill pipe or coiled tubing. For example, certain chemical treatments are facilitated by an independent fluid conduit that is externally banded to the workstring as the workstring is lowered into a well. In another example, independent conduits that are externally banded to a workstring may provide hydraulic power fluid circulation conduits for downhole motors and other power tools. Another exemplary use for an external conduit could include a protective tubing sheath for electrical or fiber optic conduit.
When it is necessary to continue the continuity of such an external conduit past or below a packer, it is preferable for the packer construction to provide an internal by-pass channel for the conduit. Hence, the external conduit follows a course between the workstring flowbore and the radially expandable sealing gland of the packer. Above and below the packer sealing gland, connectors are provided for convenient attachment of the external conduit run.
Typically, inflation or compressive expansion of a packer sealing gland is accomplished by a fluid pressure elevation within the workstring flowbore. Such selectively applied fluid pressure within the flowbore is typically applied by closing off the flowbore. This is conventionally accomplished via a wireline conveyed plug, hydromechanical valve, or by setting a “disappearing” plug into the flowbore. Alternatively, the flowbore may be closed off by depositing a bore sealing element such as a dart or ball into the flowbore and either pumping or allowing gravity to carry the sealing element against a bore closure seat below the packer. When the sealing element, for example, a ball, engages the bore closure seat, pump pressure at the surface may be transferred down the flowbore to the packer engagement mechanism. Unfortunately, this procedure leaves the bore obstructed by the sealing element for subsequent operations. Although the obstruction may be avoided or accommodated, the obstruction presence creates additional complications.
Other typical packer expansion techniques include mechanical devices that set the packer seal by rotation or a selective push or pull. Although mechanically set packers are not normally used in conjunction with external conduit due to the angular or linear displacement of the supporting workstring, expansion and rotary transition joints may be used to transcend the obstacles thereby facilitating use of the invention to activate or operate other downhole tools such as valves in conjunction with mechanically set packers.
A system has been used previously that utilized an external fluid conduit safety valve line to actuate a packer as well as to close the safety valve. In this system, the safety valve was located uphole from the packer, and both the packer and safety valve were located relatively close to the surface (i.e., within a few hundred feet). This system used a relief valve that opened to set the packer after the safety valve was closed. Aside from this system, however, it has not been generally known to actuate a packer assembly using an external conduit that is used for chemical injection, motor control, or other independent well service function.